Praise for Failed Evidence

"...A masterful expose of both the flaws in our criminal justice system and the reasons many police and prosecutors are unwilling to correct them."
Professor Christopher Slobogin, Vanderbilt University Law School

An article in today’s Wall Street Journal titled “Police Tool Targets Guns” says that the NYPD has taken delivery of a “T-Ray” scanner: a device that can detect weapons concealed under heavy clothing. The device “detects terahertz radiation, a high-frequency electromagnetic natural energy that is emitted by people and can penetrate many materials, including clothing.” The scanner “sees” the shape and size of the weapon against the body of the person carrying it, because the material of which any gun is made does not emit terahertz radiation like the human body.

NYPD Commissioner Ray Kelly said the police were very “hopeful” about the potential of the device. While the current version of the tool is “about the size of an old-style projection television,” the NYPD would like to see the technology reduced in size so that it is “small enough to carry on an officer’s gun belt.” Privacy advocates raised some concerns, but also expressed hope that the device could make the NYPD’s controversial stop and frisk program unnecessary — or at least less intrusive.

All very interesting — but to me, this isn’t new. In 1996, I published an article called “Superman’s X-Ray Vision and the Fourth Amendment: The New Gun Detection Technology” in the Temple Law Review. (The official citation is 69 Temple L. Rev. 1.) The article highlighted a nascent technology: a device that could scan people for millimeter wave radiation, emitted by all human bodies. The device used the radiation to produce images of weapons hidden under heavy clothing. The article explained the technology, described how police could use it , and explored the ways that the device would fit into the Fourth Amendment and other aspects of the law. Here’s a small slice:

[R]esearch and development efforts have begun that would give police officers something very much like Superman’s x-ray vision. Two private companies and one government laboratory, each with its own design, have started work on technology that will allow police officers to “see” through clothing to detect whether a person is carrying a concealed weapon. The idea is to produce a commercially and technologically viable device that could do an “electronic frisk” of a suspect from a distance of ten or twenty feet.

So, here we are — back to the future. The millimeter radiation technology never achieved what researchers hoped for in terms of portability — they could never make it small enough to be handheld — or in terms of use at a a distance. Perhaps the terahertz technology will do better in both respects. Assuming it does, the terahertz devices will face many of the same Fourth Amendment, legal, and privacy issues that I pointed out almost twenty years ago.